1. Field of the Invention
The present invention relates to a surgical apparatus using an ultrasonic transducer and, more particularly to an ultrasonic calculus treatment apparatus for breaking a calculus into pieces to remove the calculus.
2. Description of the Related Art
Various surgical apparatuses for endoscopically treating a calculus formed in a urinary passage or the like are being developed. Among the apparatuses, there is an ultrasonic lithotriptor (or an ultrasonic treatment apparatus) for transmitting ultrasonic vibrations to a probe (ultrasonic transmitting member) to break a calculus into pieces using the tip of the probe. Since the ultrasonic lithotriptor has characteristics that an ultrasonic energy acts only on a calculus and does not exert an influence on any biological tissue around the calculus, it is generally used. It is known that for the ultrasonic lithotriptor, a soft object such as biological tissue absorbs vibration and is not influenced by the vibration but a hard object such as a calculus is remarkably affected by a vibration energy.
Japanese Unexamined Patent Application Publication No. 62-298346 (Japanese Examined Patent Application Publication No. 06-087856) discloses an example. There is disclosed an apparatus in which a cover is disposed around a probe for transmitting ultrasonic vibrations in order to protect an inner portion of a channel of an endoscope, and the distal end of the probe is exposed from the end of the cover so that a calculus can be shattered.
In such an ultrasonic lithotriptor, as the probe for transmitting the ultrasonic vibration, a wire-shaped or pipe-shaped probe is used. Only substantially longitudinal vibration in the axial direction of ultrasonic vibration produced by an ultrasonic transducer is transmitted to the distal end of the probe, thereby shattering a calculus.
At this time, by only using the longitudinal vibration, the calculus may not be completely and efficiently shattered. For example, the calculus may be pierced in the longitudinal direction but it cannot be shattered. Accordingly, the calculus may not be easily removed from a body. Thus, it may take long time for treatment.
As disclosed in U.S. Pat No. 5,116,343, there is proposed a device in which vibration rotated about the axial direction, namely, twisted vibration (torsional vibration) is generated at the distal end of a probe to efficiently disintegrate a calculus. In the device, such a technique that torsional depressions are formed on the surface of a horn of a transducer or the distal end of the probe and simple longitudinal vibration produced by the transducer is transformed to torsional vibration at the distal end of the probe is disclosed.
However, the above-mentioned related art has a disadvantage in that the generation of the torsional vibration at the distal end of the probe is limited. In other words, when longitudinal vibration of the transducer has a phase in the extending direction, the vibration is rotated clockwise, and when the transducer has a phase in the contracting direction, the vibration is rotated counterclockwise. Namely, only the simple torsional vibration is generated.
Due to the structure, such a problem that the amplitude of the longitudinal vibration cannot be obtained enough occurs, resulting in a deterioration in efficiency of disintegration of a calculus.
U.S. Pat No. 6,161,545 discloses a surgical treatment instrument having an element for longitudinal vibration and an element for torsional vibration.
However, since means for freely changing and setting longitudinal vibration and torsional vibration is not disclosed, a function for effectively shattering a calculus may not be completed.